Electronic devices have been designed to assist and evaluate the effectiveness of physical exercise. One common device known as a pedometer counts the steps made by a user during an exercise such as running, jogging or walking. A pedometer may be worn on the user's waist or carried his pocket, and contains an accelerometer to detect variations in vertical acceleration experienced by the user, by which his steps are counted. The accelerations are roughly periodic, with the periods corresponding to the frequency of steps. The pedometer may be calibrated to the length of his stride, by dividing a specific distance by the number of steps taken to cover the distance. Subsequently, distance traveled by the user may be estimated by multiplying the number of steps by the user's stride length.
Some other devices have similar or complementary functions. U.S. Pat. No. 6,386,041 discloses a step counting device which has a ceramic vibration-detecting device, which is installed into a shoe to count the user's steps by counting the presses of the shoe against the ground. U.S. Pat. No. 6,853,955 describes a device which uses Global Positioning System (GPS) to determine the distance covered by the user on foot. However, the device is only suitable for outdoor use. U.S. Pat. No. 7,376,533 discloses a device having an acceleration sensor and a slant sensor, which can distinguish walking movements from non-walking movements if both the acceleration sensor and slant sensor detect a signal.
None of the above described devices and methods are able to distinguish between variations of exercise on foot, i.e. distinguishing running or jogging from walking. Furthermore, none of the devices and methods addresses the possibility that a user may alternate between running and walking during an exercise. Accordingly, there is a general assumption that the user moves with a constant stride length, regardless of whether he is running, jogging or walking. Thus, none of the devices and methods is able to accurately evaluate the effectiveness of an exercise on foot if the user changes pace in the exercise.
Therefore, there is a need for a method and/or device which can determine whether a person is running or walking during an exercise. Furthermore, it is desirable to provide an improved method for estimating the distanced covered by a person who alternates between running and walking.